They look a bit like everyone, which is another way of saying that they don't really look like anyone; walking blurs, like people seen in smeared mirrors, or through distorted glass. Touch them and your hand will come away covered in tiny cuts, as though you'd just run your fingers over the surface of a broken mirror. When they speak, their voices sound like the harsh, discordant scratching of glass against glass.
Here's how you call them: build a square room, and cover every inch of the walls in mirrors. Stand in the middle of the room, and fill it with light. Look in every direction and you will see yourself, reflected to infinity, a vast phalanx of your own reflections stretching away as far as you can see. Wait long enough, and you'll see that something else is walking among those reflections, something which is not the reflection of anything that is in the room with you. Call out to them, and they will come. They will step out of the mirrors as though they were made of water instead of glass.
Here's how you talk to them: you must wear a mirrored mask that covers the whole of your face. How you see through it, or around it, is your problem: some people use periscopes, others contrive primitive one-way mirrors as best they can. When the mirror-men look at you, and speak to you, they must not see anything except their own blurred-mirror faces, reflected back at them. No other method is safe.
If they see your face - if they see anyone's face - they will hunger for it. They will try to draw you into the mirrors from which they came. They will beg and plead and wheedle and promise in their horrible scratched-glass voices. They will say anything they can think of to get you to step into the mirrors with them. Finally they will use force, grabbing you with their lacerating broken-glass hands and dragging you in bodily behind them. If you enter the mirrors with them then you are lost; you will become a phantom, mad, starving, haunting the reflections in other people's mirrors until finally you wither away and die. No-one ever comes out. No-one except them.
So you don't do that. You don't let them see your face.
You can bargain with them. They can offer three services.
Here is their first service: they can spy for you. Let one step back into a mirror, then take that mirror down and hang it on another wall. The mirror-man will see everything that occurs in front of that mirror. Rehang it in your mirror-room and it will step out and tell you what it has seen.
Here is there second service: they can store for you. Hand one an object, and let it step back into a mirror, carrying the object with it. The object will now appear inside the mirror, a reflection without a source. Break the mirror and it is lost forever. Only by hanging it once again in a mirror-room and calling the mirror-men out of it can the object be retrieved.
Here is their third service: they can kill for you. Let one step back inside its mirror, and then hang the mirror in a place where you know your victim will be; and when the mirror-man sees their target they will step down from the mirror-frame, silent and gleaming, with razor-sharp knives made from mirror-shards in their hands. They can strangle with their lacerating fingers. They can exhale great clouds of ground glass dust with force enough to flay away flesh and skin. They feel no pity for innocence or youth or beauty, but they have one peculiarity, and it is this: they cannot bring themselves to kill the truly vain.
For each of these three services, the mirror-men must be paid, in the only currency that mirrors truly desire: attention. The person who bargains with them must sit and gaze upon their own reflection for a length of time commensurate to the service rendered: for a day, or a week, or a month, or a year. For great tasks - multiple murders, for example - they may demand that you literally sit and stare at yourself until you go blind. (The blind are of no further use to them, and cannot enter into any subsequent bargains.) Payment is rendered after the fact, but it is unwise to attempt to cheat them. They can step out of any reflective surface, at any time, and they will drag the defaulter away to complete their service... on the other side of the mirror. That such a person can never return home afterwards is no concern of theirs.
(There are some wicked old magicians who live in houses where every reflective surface is forbidden. No polished metal, no glass, no still water except in darkened rooms. They are hiding from the mirror-men. Not so much as a bowl of wine is to be placed on a well-lit table, in case a shining arm reaches out of it to grab them by the throat.)
Some curious souls have asked them about their lives on the far side of the mirror. For such questioners, the mirror-men spin elaborate tales of shining glass cities, gleaming and windless oceans, radiant kings and queens. They tell their stories in stagy, rehearsed voices, like people practising speeches in front of mirrors. If the questioner expresses doubt, the mirror-men will be most offended. When, they will ask, has a mirror ever been known to lie?
What they neglect to mention is that, while mirrors tell the truth, they only ever tell it backwards.
- Mirror-Men: AC 15 (lightning reflexes), 2 HD, +4 to-hit, 2 mirror-shard knives (1d6+1/1d6+1), saves 12, morale 8, special attack: ground glass breath, special defence: spell reflection, looking-glass leap. They take double damage from crushing attacks. Anyone in skin-to-skin contact with them takes 1 damage per round from hundreds of tiny cuts.
Ground-glass Breath: Instead of making its normal attacks, a mirror-man can exhale a blast of ground glass into the face of someone within 10'. The target must save or take 1d8 damage and be blinded; a Cure Light Wounds spell cast on their eyes will heal the blindness, although not any other damage.
Spell Reflection: Any single-target spell cast on a mirror-man, whether beneficial or harmful, will automatically bounce back and affect the person who cast it, instead. Area-effect spells are not affected by this ability.
Looking-Glass Leap: A mirror-man may leap into any reflective surface large enough for it to physically dive into: a polished shield, a pool of still water, etc. It then 'inhabits' that object, and can leap back out of it at any time, cured of all wounds. It can also leap at will from one reflective object to another, provided the first is reflected in the second. (So a mirror-man inhabiting a polished shield could leap into a window-pane, instead, if the shield was reflected in the glass for even a single moment.) When fighting a mirror-man, smashing whatever shiny thing it just jumped out of should probably be your top priority.